A groundbreaking study to be published in the Journal of the American Veterinary Medical Association (JAVMA) shows that furosemide does more than enhance performance in Thoroughbred racehorses; it also has beneficial effects on the health and welfare of those horses.

Most countries ban the race-day use of furosemide because it improves performance in racehorses. Only the United States, some South American countries, including Brazil, and some tracks in Canada, allow the use of furosemide on race day.

"The data in the study provides the most reliable information to guide the highly politicized debate over use of furosemide in horses," says Dr. Kenneth Hinchcliff, professor and dean of the Faculty of Veterinary Science, The University of Melbourne, and co-author with Professor Paul Morley, Colorado State University, and Professor Alan Guthrie, University of Pretoria in South Africa. "To date, there has been only a limited amount of high-quality evidence - and none matching the quality of this study - to inform the debate. We know that furosemide is associated with improved performance, and that exercise-induced pulmonary hemorrhage (EIPH) markedly affects race performance. But we didn't know the answer to the third - and most important - leg of the trifecta: Whether furosemide is effective in treating EIPH. We now know."

The study, "Efficacy of furosemide for prevention of exercise-induced pulmonary hemorrhage in Thoroughbred racehorses," which will appear in the July 1, 2009, issue of the JAVMA, is the first of its kind to draw a definitive link between the use of the drug and the prevention of the bleeding condition in Thoroughbreds.

The study included 167 Thoroughbred racehorses that performed under typical racing conditions in South Africa between Nov. 20 and Nov. 28, 2007. Each horse in the study raced twice, once after receiving furosemide before the race and once after receiving a placebo. The results showed that horses were 3 to 11 times as likely to have EIPH after placebo administration as they were after administration of furosemide. In addition, about two-thirds of the horses that had EIPH after administration of the placebo had a reduction in EIPH severity when treated with furosemide.

Hinchcliff, Morley and Guthrie conducted what is considered the "gold standard" of scientific studies, performing a well-designed, randomized, controlled clinical trial.

The study was truly an international collaboration.

"The study could not have been conducted without the strong support of the racing industry, both through the Grayson-Jockey Club Research Foundation and Racing Medication and Testing Consortium in the United States, and the racing industry in South Africa," said Guthrie.

"This study design is similar to those used to test the efficacy of treatment in human medicine," Morley said. "To date, such studies have been uncommon in veterinary science, and we believe that our study is unique among studies of drug efficacy in racehorses under conditions of racing. The rigorous approach to study design resulted in a very clear result."

Once the study results are widely circulated, the authors anticipate that some racing jurisdictions may reconsider their ban on the use of furosemide.

"It is likely that racing jurisdictions will reconsider, in one way or another, their position on the use of furosemide," they said. "However, the decision to allow or disallow the use is based on the balance of a number of factors, and resolution of this complex situation will take some time."

"The challenge will now be for countries such as England, Hong Kong, Australia and South Africa that do not currently permit race-day use of furosemide. The challenge that they will face is balancing the animal-welfare aspect of being able to prevent or reduce the condition against the imperatives for drug-free racing. Additionally, instituting race-day administration of furosemide would be a significant added expense to racing."

Source
AVMA